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NEW YORK STATE MUSEUM 



example as we will find anywhere among the class of a " single 

 bone." One not acquainted with its composition in the nestling 

 would never suspect anything else after careful examination. The 

 inturned tips of either articular end are at right angles to the median 

 plane. Each presents an elliptical pneumatic foramen just within 

 the tip. Concave articular facets are seen, which correspond to the 

 convex surfaces, as described on the foot of each quadrate. There 

 is a rudimentary " posterior articular process " present. The coro- 

 noid process, on either ramus, is but feebly developed and only 

 slightly elevated above the general line [fig. 24]. When articulated 

 with the skull the superior line of the ramus ceases to be approxi- 

 mated to the osseous superior mandible at a point on the middle of 

 the dentary process of that bone. From this point it curves gently 

 downward until at the tips of each mandible they are four milli- 

 meters apart. This condition is seen in the Cathartidae also. 



In the hyoid arches we find that the glos- 

 sohyal remains in cartilage throughout life 

 [fig. 22]. The ceratohyals or "lesser cornua" 

 are quite individualized, being simply con- 

 nected by a transverse bar at their middles, 

 affording the articular facet for the basihyal. 

 This latter element is coossified with the basi- 

 branchial or urohyal, the two bones forming 

 one piece in the adult harrier. The cerato- and 

 epibranchial elements are upcurved, slender, 

 cylindrical rods of bone, the latter being 



Fig. 24 Mandible of Cir- J . & 



cus seen from above. Life slightly tipped with cartilage on their pos- 



size from nature terior extre mitieS. 



Circus presents the desmognathous type of structure so far as its 

 palate is concerned, and falls within the group Aetomorphae of 

 Huxley. 



The desmognathism in Circus, and the union of its maxillopala- 

 tines with the nasal septum takes place beyond the broad processes 

 thrown ofif by the maxillaries, while the spongy parts of the maxillo- 

 palatines are produced far backward with a narrow valley between 

 them. 



The arrangement is very different in Falco, where the fusion of the 

 maxillopalatines is entirely opposite the maxillary processes, if any- 

 thing somewhat more posterior to them, and, after their separation, 

 the intervening valley is much wider. 



